8 Ways to Compost

Want to compost, but not sure where to start? Confused about the difference between hot compost and cold compost? Considering worm composting, or perhaps even grub composting?

Whether you have a gigantic garden and oodles of time and energy, or a balcony and an overbooked schedule, there is a composting technique that is right for you. Here’s a tour of the most common—and some more unusual—forms of composting.

Hot composting is not rocket science, and it doesn’t require expensive equipment or capital outlay. But it does need some careful attention, and the ability to gather significant amounts of the right kinds of biomass.

You need to mix significantly more carbon-rich, woody “brown” materials with smaller amounts of nitrogen rich “greens” (kitchen scraps, lawn clippings etc). How exact you want to be is up to you, but the correct ratio is about 25 parts carbon to 1 part nitrogen. (For the truly geeky, a friend of mine has even created an iPhone app to help you maintain compost ratios!)

You will also need to spend some time turning the heap every few weeks.

While managing these hot compost bins in his community garden, fellow TreeHugger Chris Tackett found that communication is as important as building the heap itself:

“The challenge with composting in a community garden smack dab in the middle of a neighborhood is getting everyone informed about the process and where things like food scraps and grass clippings should go.

“With the “hot” bins, I wanted to layer them with the right mix of browns and greens and then let them process and break down before adding loads of new material, so we’re trying some signage to explain which bins are ‘active’ and where extra browns and vegetable peelings should go.”

With a really hot heap, in the right conditions, you may achieve usable results in just a few months.

Cold composting is much less-labor intensive, but considerably slower than hot composting methods. Composting bins, or piles, are simply filled up as compostable materials become available. Compost can be harvested gradually as it becomes ready by digging from the bottom of the heap. (This is much easier with a commercial composter like the one pictured here, or a custom-built one that also allows access to the base.)

Alternatively, you can build up one cold compost heap or bin over a season, and then let it sit while you start filling up the next. In my experience it can take up to a year, using this method, to achieve good, usable compost.

It’s worth noting that cold composting will be unlikely to kill weed seeds or plant diseases, so it is worth being careful about what you put in your bin. On the other hand, however, I have heard some permaculture enthusiasts argue that a cold heap will have more beneficial microorganisms that can actually live outside of the composting environment. (I am skeptical about this claim. Even hot heaps cool down and go through a secondary, cooler decomposition.)

Because cold composting doesn’t involve turning the pile, getting enough oxygen to avoid anaerobic decomposition (and the slime and smell that goes with it) can be tricky. One of the best methods is to simply add plenty of scrunched up newspaper, cardboard and other high-fiber, carbon-rich materials in with your kitchen scraps and other waste.

Cold composting is great for folks who may not generate huge amounts of organic waste at any one time, or those who simply don’t have the time, energy or interest for more involved methods. But be prepared to wait if you want to use the end result.

Worm composting, or vermicomposting, is a much touted solution for indoor composting, or those with little space. Commercially available worm composters can be purchased from garden stores, or online, or a simple system like the one pictured can be built using a few plastic tubs, and some newspaper.

When Chris is not managing hot compost heaps at his community garden, he composts his own waste in a DIY worm composter: “The worm bin could not be any easier. I made a really basic setup using two nested plastic tubs and the worms love eating some of my kitchen waste, like apple cores, carrot tops, veggie peels, etc. Everyone should do this to reduce the amount of trash that rots in the landfills.”

The techniques used to make leaf mold are very similar to those used to make cold compost—essentially you just pile it up and let it rot. But because leaves fall at the same time of year, this usually involves building a large pile and then allowing it to break down, rather than adding to the heap over time.

Because making leaf mold is a cold process, and because there are relatively few nutrients that could wash away, there is no need to cover the heap or otherwise insulate it. In fact, regular soakings from rain will help the pile to break down, Most leaf mold containers are little more than a set of posts with some chicken wire attached.

While the end result is much less nutrient-rich than compost, this is no bad thing. Leaf mold is often used as a mulch, or can be mixed with compost to make potting soil. And it can also be added in larger quantities than compost or manure to garden beds as a soil improver without a concern for overfeeding plants or washing away nutrients.

The bin shown here contains one year’s worth of leaves raked up from my yard. I expect it to be ready to apply by the end of the next growing season. Really, anyone with excess leaves and a garden should be making leaf mold. Even a small circle of chicken wire can be used to make small quantities for potting soil.

This rather space-age looking contraption is the BioPod Plus, a commercially available grub composter.

Using the larvae of the black soldier fly (yeah, sounds yucky doesn’t it?), it can transform organic waste like whole dead fish, vegetable scraps, manure and even human feces into protein and plant food in a matter of days. The end result is not so much compost, but rather a liquid plant food, and a whole ton of grubs that can then be fed to chickens, fish or even wild birds. Some say they can even be a great feedstock for biodiesel.

This video on grub composting shows just how fast these things work. And for anyone that feels icky about touching live grubs, the BioPod is designed so that mature grubs “auto harvest” into a separate collection bucket.

Compost tumblers offer a convenient, labor-saving alternative to turning a hot compost heap—and they help to break down compost a lot faster than a cool heap too. They work by allowing the gardener to turn the unit regularly and easily, mixing up the contents and providing oxygen to the microorganisms it contains. (They can be a great solution for folks with back problems.)

The number of commercially available designs is astounding, ranging from cool-looking balls, to “hybrid” tumbler and rainwater catchment units. Compost Mania has a comprehensive selection of compost tumblers available online, and most garden centers and hardware stores will stock a few examples.

But be warned—most commercial tumblers do not come cheap. ($250 seems to be a typical starting price.) DIY enthusiasts may want to check out this video/post on how to build your own compost tumbler.

Humanure Composting

This one is probably not for the squeamish. But with astounding amounts of fresh water being flushed down the toilet everyday, and fertilizer becoming an ever-more-precious resource, more and more people are turning to the idea of human waste as a valuable commodity.

If you want to start small, just go ahead and pee on your heap. Urine is a great compost activator, and a source of phosphate and nitrogen. But ladies, you should know that male pee may be better for the heap than female pee. (At least we boys are good for something…)

But for those who take the idea of composting human waste seriously, a composting toilet is the way to go. The humanure system was pioneered by Joseph Jenkins of The Humanure Handbook.

In The Humanure Handbook, waste is transported regularly from the household to the compost heap and then turned to ensure a hot decomposition.

Jenkins sells a “Loveable Loo” (video shown here) that is supposed to make waste collection and transportation relatively hassle free.

Anyone wanting to attempt humanure composting or composting toilets should do some reading first, and establish their comfort zone in terms of contact with poop, and safety.

Most composting toilet advocates suggest the end result should not be used on parts of plants that will be eaten directly (eg carrots or lettuce), but rather fruit trees or bushes where no contact between poop and food is likely to happen. You should also do some research into legalities and planning issues in your area, although there are plenty of people with humanure toilets in the heart of the city.

Finally, it’s worth noting that you don’t have to do it all yourself. Yes, there are many wonderful—and surprisingly easy—ways to incorporate composting into your own garden, or even indoors for the gardenless.

But with municipal composting taking off in cities around the world, you may be able to simply have your organic waste collected along with your recycling. (And if you can’t, you should raise a stink with your local authorities until you can.)

Although you won’t get to use the free soil improver with municipal composting, and you’ll miss out on all the fun of reflecting on compost as a form of animal husbandry, you’ll still sleep better knowing that your waste food isn’t contributing to landfill runoff or methane emissions.